The present invention relates generally to motor mounting arrangements for mounting an electric motor to a supporting structure, such as a blower housing, and in particular to mounting bands which are adjustable so as to accommodate motors of various diameters.
In air moving systems incorporating blowers, the blower wheels are supported within blower housings which are typically dimensioned and positioned such that relatively close running tolerances are maintained in the interest of maximizing blower efficiency. In direct drive applications, the motor is suspended from the blower housing scroll, and a motor shaft in turn supports and drives the blower wheel within the housing. This type of direct drive arrangement is very desirable because of its relative simplicity and economy as compared with belt and pulley arrangements, and the like. Examples of products wherein mounting arrangements of this type are utilized include furnaces, and could also include room air conditioners, etc.
In applications wherein a blower wheel is mounted directly to a motor shaft, it is very desirable to isolate motor vibrations from the housing structure so as to minimize the transmission of noise thereby achieving quieter operation. Not only must mounting arrangements reduce the transmission of motor vibrations, but they must provide sufficient mounting rigidity to avoid excessive axial and tilting movement of the motor during operation and shipping. To achieve these ends, mounting arrangements have been developed comprising mounting arms which have low torsional spring constants, and yet have sufficient strength to withstand shipping and handling loads for the motor and blower assemblies. The spring constants of the mounting arms for the axial, radial and tilting vibration modes are selected so that the characteristic vibration transmissibility ratios for these modes are close to unity. However, the characteristic torsional mode of vibration transmissibility is substantially less than unity because of the flexibility of the arms. Such prior art mounting arrangements are disclosed in Litch U.S. Pat. No. 4,063,060 and Dochterman U.S. Pat. No. 4,076,197 which are owned by the assignee of the present application. The entire disclosures of those two patents are also incorporated herein by reference.
In many instances, it is desirable to permanently attach the mounting arms to the motor shell when manufacturing original equipment motors. For replacement or aftermarket motors, however, motors are sometimes mounted by means of bolts, welding straps, or bands removably affixed to the shell. This sometimes is thought to afford more flexibility in handling replacement motors.
One prior art arrangement for mounting motors, particularly replacement motors, to blower housings or other mounting structures comprises a belly band which encircles the motor shell and is tightly secured thereto by means of a band tightener. One example of this type of mounting arrangement is disclosed in Litch U.S. Pat. No. 4,063,060.
The bolt holes on the blower housing, to which the mounting arms or lugs are secured, are generally arranged in a circular pattern along the curved scroll which defines the air inlet at one side of the housing. Accordingly, in order for the motor to be properly installed on the blower housing, the corresponding bolt holes on the mounting arms must match up with the bolt holes on the housing. Motor mounting adaptor kits of the belly band type discussed above have been used in the industry, but these kits generally are suitable only for a particular motor diameter and a particular bolt hole spacing and circumference. Thus, a large inventory of such mounting kits is required to accommodate the wide variety of motor sizes and bolt hole spacings and circumferences which may be encountered.
The belly band type of mounting kits that utilize radiator hose clamp types of bands partially overcome some of the disadvantages of non-universal kits by providing a band which is infinitely adjustable by virtue of a screw-type band tightener. The mounting arms, however, can be positioned at any point around the circumference of the band. This might require the installer to rough position the mounting arms on the band, partially tighten the band, place the motor and mounting structure into the blower inlet to determine whether or not the openings in the arms coincide with the bolt hole openings, perhaps readjust the position of the arms, and then make a further visual determination as to whether or not they match up. This procedure could be unwieldly, and require additional time to obtain a proper fit between the mounting structure and bolt holes.
It is an object of the present invention to provide a motor mounting arrangement of the band and mounting arm type wherein the mounting arrangement is suitable for use with different motor shell diameters and bolt hole circumferences and spacings.
It is a further object of the present invention to provide such a motor mounting arrangement wherein the mounting arms can be quickly located and positively locked at the proper circumferential positions on the band for a plurality of band circumferences, thereby insuring proper alignment between the bolt holes in the mounting arms and the bolt holes in the blower housing.
A still further object of the present invention is to provide a motor mounting arrangement which is quickly and easily installed onto a replacement motor, and yet provides the torsional, axial, tilting and radial vibrational and shock characteristics provided by the mounting arrangements disclosed in the aforementioned U.S. Pat. Nos. 4,063,060 and 4,076,197.